2.4733 / UNS N06230 / NiCr22W14Mo Forging Parts

What is 2.4733 / UNS N06230 / NiCr22W14Mo?

2.4733 is the German Werkstoffnummer (material number) listed in DIN 17744 for the wrought nickel-base superalloy whose chemical designation is NiCr22W14Mo and whose American UNS number is N06230. The same chemistry is marketed generically as Alloy 230. It is a solid-solution-strengthened alloy: unlike precipitation-hardening grades such as Inconel 718 or 17-4PH, it is not age hardened. Its strength comes from three mechanisms working together:

• Tungsten and molybdenum in solid solution (nominally 14 % W + 2 % Mo) distort the nickel lattice and slow dislocation motion. This is the dominant strengthening mechanism at temperature.
• Primary M₆C carbides, tungsten-rich and formed on solidification, pin grain boundaries and limit grain growth during forging and annealing.
• Secondary M₂₃C₆ carbides precipitate on the grain boundaries in service between roughly 760 and 980 °C, contributing much of the alloy's creep resistance.

The 0.005–0.05 % lanthanum addition is small but decisive. Lanthanum is a reactive rare-earth element that segregates to the metal–oxide interface and chemically keys the Cr₂O₃ scale to the base metal, so the scale survives thermal cycling instead of spalling. This is why 2.4733 outperforms most nickel alloys in cyclic furnace and combustor duty, where the failure mechanism is repeated scale loss rather than steady-state oxidation.

The second distinguishing property is thermal stability. Many high-temperature nickel and cobalt alloys form brittle intermetallic sigma (σ) or mu (µ) phases after long exposure in the 650–870 °C range, so a component that passes acceptance testing can be embrittled after a year in service. 2.4733 does not: published long-term exposure data show retained room-temperature ductility after many thousands of hours in that band. For a forged component that must remain repairable and impact-tolerant over a 20-year plant life, that behaviour is often more important than a marginal creep-strength advantage.

Finally, 2.4733 is one of the few nickel alloys with genuinely good nitriding resistance, which is why it became the standard material for catalyst-support grids and baskets in ammonia-oxidation (nitric acid) plants, and for furnace hardware operating in dissociated ammonia.

Which 2.4733 forged forms can Jiangyin Jiangnan Metal supply?

Jiangyin Jiangnan Metal produces 2.4733 / UNS N06230 by three routes, chosen by geometry and quantity. Open-die forging covers shafts, blocks, discs and stepped bodies. Seamless ring rolling produces rings and ring-rolled flange blanks and is the most common route for combustor casings, catalyst-grid support rings and pressure-housing rings. Upset forging is used for short, large-section hubs and tube-sheet blanks. Because nickel-alloy billet is expensive, we quote near-net-shape wherever the profile allows. On ring and disc geometries this typically removes 25–45 % of the machining stock a rectangular blank would need.

What are the equivalent designations for 2.4733?

Engineers reach this chemistry through at least a dozen names depending on which standards body, mill or OEM wrote the drawing. Every designation in the table below refers to the same alloy chemistry, and Jiangyin Jiangnan Metal accepts purchase orders under all of them, cross-certifying on a single material test certificate where the chemistry and mechanical results satisfy more than one specification.

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What is the chemical composition of 2.4733 / UNS N06230?

The composition limits below are the nominal wrought limits for UNS N06230 / W.-Nr. 2.4733, and are what Jiangyin Jiangnan Metal orders billet to. Chromium provides the protective Cr₂O₃ scale; tungsten and molybdenum give solid-solution strength; carbon forms the M₆C and M₂₃C₆ carbides; aluminium assists oxidation resistance; and lanthanum anchors the oxide scale during thermal cycling.

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Why the lanthanum specification matters on your purchase order

Lanthanum is the single most commonly mis-specified element in this alloy. The permitted range is 0.005–0.05 %, a factor of ten. Heats at the bottom of the band still pass a certificate of conformity, but cyclic-oxidation life in a thermally cycled combustor or radiant tube is measurably shorter than heats at mid-band. If your component sees more than roughly one thermal cycle per day to above 900 °C, state a minimum lanthanum of 0.015 % on the enquiry so the billet can be selected accordingly. We will report the actual analysed value on the certificate either way.

What are the mechanical properties of 2.4733 at temperature?

The values below are typical solution-annealed tensile properties for 2.4733 / UNS N06230 from room temperature to 1093 °C (2000 °F). They are the figures Jiangyin Jiangnan Metal uses for enquiry screening. They are typical values, not guaranteed minima. The guaranteed minima for a specific order are those of the ordered specification (ASTM B564 or AMS 5891) at room temperature, plus any elevated-temperature acceptance values written into the purchase order.

↔ Swipe the table sideways to see all temperatures.

Reading the table: the yield-strength anomaly at 760 °C

Notice that 0.2 % yield strength rises from 303 MPa at 649 °C to 324 MPa at 760 °C before falling away. That is not a data error. It is dynamic strain ageing. In this temperature window, solute atoms (principally carbon, and the substitutional tungsten and molybdenum) become mobile enough to diffuse to moving dislocations and pin them during the tensile test. The alloy resists initial plastic flow harder than it did 100 °C cooler. Elongation peaks in the same region for the same reason.

Two practical consequences follow for a forged component. First, do not use yield strength as a proxy for load capacity above roughly 650 °C. Above that temperature the component is governed by creep, not by yield; a part stressed below yield will still deform over time. Second, the 650–815 °C band is where machining and straightening of 2.4733 is at its most difficult, because the same mechanism raises flow stress and promotes built-up edge. Straightening operations should be done either hot (above 900 °C) or cold, not in between.

How does 2.4733 behave in creep and stress rupture?

Above about 650 °C, a 2.4733 component fails by creep long before it reaches its tensile strength. Design is therefore governed by time-dependent allowables: the stress that produces rupture, or a specified creep strain, in the intended service life at the intended metal temperature. The alloy's creep resistance comes from the tungsten in solution plus the grain-boundary carbide network, which is why grain size matters more in this alloy than in most forgings we make.

A convenient way to compress creep data across temperature and time is the Larson-Miller parameter (LMP), defined as P = T × (C + log₁₀ t) where T is absolute temperature in kelvin, t is rupture time in hours and C is a material constant, conventionally 20 for nickel alloys. Rupture data at many temperature/time combinations collapse onto a single stress-versus-LMP curve, so one curve can answer "how long at what stress" for the whole envelope. The estimator below implements that correlation for 2.4733.

What are the physical properties of 2.4733 / UNS N06230?

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Because the alloy is non-magnetic, magnetic-particle inspection cannot be used on 2.4733. Surface examination must be by liquid penetrant (ASTM E165 / EN ISO 3452) and volumetric examination by ultrasonics (EN 10228-3, SEP 1921 or ASTM A388) or radiography. Purchase orders that carry a boilerplate "MT per ASTM E1444" clause written for steel forgings have to be corrected before production. We flag this at order review, but it is worth catching at your end first.

How does 2.4733 resist oxidation, nitriding and other high-temperature attack?

2.4733 protects itself with a continuous chromia (Cr₂O₃) scale, reinforced by the aluminium addition and mechanically keyed to the substrate by lanthanum. That combination is what makes it a first-choice alloy in oxidising and, unusually, nitriding atmospheres. It is much weaker in sulphur-bearing and molten-salt environments, and it is not intended for aqueous acid service at all.

2.4733 vs Inconel 617, Hastelloy X, Incoloy 800HT, Inconel 625 and Haynes 25

The honest comparison below is the one we give customers at enquiry stage, including the cases where 2.4733 is the wrong choice. Cost index is relative to Incoloy 800HT as the baseline for forged product in comparable quantities; it moves with the nickel, chromium, tungsten and cobalt markets, so treat it as a ranking rather than a price.

↔ Swipe the table sideways to see all six alloys.

How is 2.4733 forged, heat treated, welded and machined?

Forging practice

2.4733 is forgeable but unforgiving. The tungsten content narrows the hot-working window and raises flow stress sharply as the billet cools, so the discipline that matters most is temperature control between blows, not press capacity. Our standard practice for this grade:

Two failure modes account for most rejected superalloy forgings, and both are temperature discipline problems. Edge and surface cracking comes from continuing to work material that has dropped below about 1010 °C. The remedy is more reheats, not more force. Centre bursts come from taking heavy reductions on a billet whose core has not reached soak temperature; because 2.4733 conducts heat poorly, the surface can look ready long before the centre is. We soak by calculated time-at-temperature per section, not by appearance.

Heat treatment

The standard and normally the only condition for 2.4733 is solution annealed: 1177–1246 °C followed by rapid cooling. The purpose is to dissolve grain-boundary carbide networks formed during forging and cooling, put the tungsten and molybdenum back into solution, and set the grain size. There is no ageing treatment. Attempting to age this alloy the way you would age 718 or 17-4PH does nothing useful and, if held in the 760–870 °C band, will coarsen grain-boundary carbides and reduce room-temperature ductility. Annealing temperature is the lever for grain size: the low end of the range for finer grain and better ductility, the high end for coarse grain and maximum creep life.

Welding

2.4733 welds readily by GTAW, GMAW, SMAW and plasma-arc processes. Matching filler is AWS A5.14 ERNiCrWMo-1 (bare wire, AMS 5839) or AWS A5.11 ENiCrWMo-1 (covered electrode); the ISO designations are SNi6231 and ENi6231. Because the alloy is solid-solution strengthened rather than age hardened, post-weld heat treatment is not normally required for the alloy itself. A full solution anneal is worthwhile after heavy cold work, after extensive repair welding, or where the fabrication code demands it.

• No preheat is required. Keep interpass temperature below about 100 °C. Nickel alloys have no hydrogen-cracking problem but do suffer from heat build-up and distortion.
• Low heat input, stringer beads, minimal weaving. Wide weaves promote centreline hot cracking in high-tungsten weld metal.
• Cleanliness is not optional. Sulphur, lead, zinc and low-melting-point contamination cause liquation cracking in the heat-affected zone. Degrease and wire-brush with a dedicated stainless brush; keep the joint free of marking crayon and galvanised fixturing.
• Back purge root passes with argon to prevent chromium oxidation on the underbead.
• Weld metal creep strength approximately matches base metal; the practical weak link on a creep-limited component is usually the coarse-grained heat-affected zone, so keep weld locations away from peak-stress regions where the design allows.

Machining

2.4733 machines like a tough, work-hardening superalloy: roughly 12–15 % of the machinability of free-cutting steel. The two rules that matter more than any speed-and-feed table are never dwell (a stationary tool against the workpiece work-hardens the surface and destroys the next pass) and rigidity beats speed. Take a heavy positive feed at modest surface speed rather than a light feed at high speed.

Production capability for 2.4733 forgings

Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging works in Zhouzhuang Town, Jiangyin City, Jiangsu Province, employing about 460 people including 9 senior and 32 intermediate engineers. The plant covers raw material, forging, heat treatment, machining, testing and inspection in-house, which is what makes tight control of a difficult grade like 2.4733 practical.

Forging and heat-treatment equipment

Size envelope

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Nickel-alloy limits are narrower than the plant envelope for a physical reason, not a commercial one: 2.4733 has a much higher flow stress and a much narrower working window than carbon or alloy steel, so the same press delivers less useful reduction per blow and more reheats are needed. Anything close to the figures above should be discussed with our engineering team before you design around it.

Which standards, testing and certificates apply to 2.4733 forgings?

For a forged component in this grade, the specification that governs is almost always ASTM B564 / ASME SB-564 (general industrial and pressure work) or AMS 5891 (gas-turbine and aerospace). Bar stock is ordered to ASTM B572. European projects normally reference the DIN 17744 material number 2.4733 alongside the ASTM specification rather than instead of it.

What appears on the certificate

• Heat number and full chemical analysis against the ordered specification, including the actual analysed lanthanum value.
• Melting route (EAF + AOD/VOD + ESR, or VIM + ESR / VIM + VAR where specified).
• Solution-annealing temperature, soak time and cooling method, with furnace chart records retained.
• Room-temperature tensile results (and elevated-temperature results where the order calls for them), hardness and grain size to ASTM E112.
• Ultrasonic examination report to the ordered acceptance class, and liquid-penetrant results where specified.
• Equivalent-designation statement where a single heat satisfies more than one specification.
• EN 10204 3.1 as standard; EN 10204 3.2 countersigned by TÜV, DNV, BV, Lloyd's Register or ABS on request.

Quality gates and non-conformance handling

How to specify a 2.4733 forging order

Ten mistakes engineers make when ordering 2.4733 forgings

1. Ordering by trademark instead of by chemistry. A purchase order requiring "HAYNES® 230®" can, strictly, only be filled by Haynes International. Specify UNS N06230 / 2.4733 / NiCr22W14Mo to ASTM B564 instead. That is the generic chemistry any qualified producer can supply, and it is what belongs on the drawing.
2. Specifying an ageing treatment. 2.4733 is not precipitation hardened. Ageing cycles copied from an Inconel 718 or 17-4PH specification do nothing for strength and, if they land in the 760–870 °C band, coarsen grain-boundary carbides and reduce room-temperature ductility.
3. Leaving grain size unspecified on a creep-limited part. Fine grain gives better ductility and fatigue life; coarse grain gives longer creep life. They are produced from the same heat by different forging and annealing practice. Say which you want, or accept a general-purpose ASTM 4–6.
4. Specifying magnetic-particle inspection. The alloy is non-magnetic. MT is physically impossible. Use liquid penetrant.
5. Designing to yield strength above 650 °C. Above roughly 650 °C the component is creep-governed. A part stressed comfortably below the yield strength in Table 3 will still deform over a design life. Use rupture and creep-strain allowables, not tensile data.
6. Ignoring the lanthanum band on cyclic duty. Lanthanum may legitimately be anywhere from 0.005 % to 0.05 %. On thermally cycled combustor and furnace hardware, ask for a minimum of 0.015 %.
7. Assuming it resists sulphur and molten salts. Excellent in oxidising and nitriding atmospheres is not the same as excellent everywhere. Sulphidising and molten-ash environments need a different alloy or a coating strategy.
8. Using it as a wet-corrosion alloy. For hot acids and chloride solutions the answer is C-276, Alloy 59 or 625, not 2.4733.
9. Abrupt section changes on thermally cycled parts. With thermal conductivity at 8.9 W/m·K, sharp section transitions concentrate thermal stress. Radius them generously. This is the single most valuable design change on furnace and combustor hardware.
10. Forgetting the cobalt cap for nuclear service. Cobalt is permitted up to 5 % as a residual. In neutron flux it activates to Co-60. If the component goes into a reactor environment, state a maximum cobalt limit (commonly 0.20 % or 0.05 %) explicitly on the enquiry, because standard heats will not meet it.

Drawing callout template for 2.4733

Copying the block below into a drawing's material note removes most of the ambiguity that causes change orders on this grade. Adjust the annealing target, grain size and NDE class for your application.

MATERIAL:      UNS N06230 / W.-Nr. 2.4733 / NiCr22W14Mo
               per ASTM B564 (or AMS 5891 for gas-turbine work)

MELTING:       Double melted — EAF + AOD/VOD + ESR minimum
               (VIM + ESR or VIM + VAR where specified)

CONDITION:     Solution annealed 1177-1246 °C, rapid cool
               NO AGEING TREATMENT — alloy is solid-solution strengthened

GRAIN SIZE:    ASTM E112 grain size 3-5 (creep-limited parts)
               or 5-7 (ductility / fatigue-limited parts)

CHEMISTRY:     Lanthanum 0.015 % min for thermally cycled service
               Cobalt 0.20 % max for nuclear service (state if required)

NDE:           UT per EN 10228-3 quality class 3 (or SEP 1921 / ASTM A388)
               PT per ASTM E165 Type I Method C
               MAGNETIC PARTICLE NOT APPLICABLE — alloy is non-magnetic

CERTIFICATION: EN 10204 3.1 mill certificate
               (3.2 with third-party witness on request)

MARKING:       Heat number, specification, condition and drawing number
               vibro-etched or low-stress stamped on a non-functional face

Failure modes in 2.4733 service and how to design them out

Where are 2.4733 forgings used?

The applications below are the service environments in which 2.4733 forgings are most commonly specified. Project references and named case studies are available on request, subject to customer confidentiality.

Jiangyin Jiangnan Metal Co., Ltd. (2026). "2.4733 / UNS N06230 / NiCr22W14Mo
Forging Parts — technical datasheet and forging capability." Updated 10 August 2026.
https://www.steelforgepieces.com/Nickel-Alloy/2.4733.html

Glossary

2.4733

German Werkstoffnummer per DIN 17744 for the nickel-chromium-tungsten-molybdenum alloy designated NiCr22W14Mo. Identical chemistry to UNS N06230.

UNS N06230

Unified Numbering System designation for the same alloy. The designation to put on a drawing if you want a generic, unrestricted specification.

NiCr22W14Mo

The DIN chemical designation, read directly as nickel with 22 % chromium, 14 % tungsten and molybdenum.

Solid-solution strengthening

Strengthening from dissolved alloying elements, here tungsten and molybdenum, distorting the lattice, rather than from a precipitated second phase. It is why this alloy cannot be age hardened.

M₆C carbide

Tungsten-rich primary carbide formed on solidification. Pins grain boundaries during forging and annealing, limiting grain growth.

M₂₃C₆ carbide

Chromium-rich secondary carbide that precipitates on grain boundaries in service between roughly 760 and 980 °C, contributing much of the creep resistance.

Dynamic strain ageing

Interaction of mobile solute atoms with moving dislocations during deformation, producing the yield-strength rise seen around 760 °C and making machining harder in that band.

Larson-Miller parameter

Time-temperature parameter P = T(K) × (C + log₁₀ t), conventionally with C = 20 for nickel alloys, used to collapse creep-rupture data across temperature and time onto one curve.

Sigma (σ) and mu (µ) phase

Brittle intermetallic phases that embrittle many high-temperature alloys after long mid-range exposure. 2.4733 is notable for resisting their formation.

Solution annealing

Heating to 1177–1246 °C and cooling rapidly to dissolve carbide networks, restore a uniform solid solution and set grain size. The standard delivery condition for this grade.

EN 10204 3.1

Inspection certificate issued by the manufacturer's own independent inspection department, giving actual test results on the delivered material.

EN 10204 3.2

Inspection certificate additionally countersigned by an independent third party or the purchaser's authorised representative.

Frequently asked questions about 2.4733 / UNS N06230

Technical references